Solar atmospheric coupling by electrons (SOLACE): 2. Calculated stratospheric effects of precipitating electrons, 1979–1988

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Abstract
An analysis has been carried out of the effects of energetic electron precipitation (EEP) on stratospheric NOy, NO2, and O3. Solar wind observations used together with precipitating electron fluxes observed aboard TIROS spacecraft show a close relationship between the long‐ and short‐term fluctuations in the solar wind and EEP over a period of 16 years. Daily electron energy spectra for 4.25≤E≤1050 keV and energy deposition profiles are developed for both hemispheres for L≥5 and used in two‐dimensional chemical transport simulations for the period January 15, 1979, through December 31, 1987. Results indicate that globally averaged column NOy (from 25 to 40 km) increases by ≈ 12% between 1979 and 1983–1985 with a rapid decline to 1979 levels between early 1985 and 1987. Day‐by‐day comparisons of the results with the Stratospheric Aerosol and Gas Experiment (SAGE II) column NO2 and O3 for the period October 24, 1984, and December 31, 1987, show good agreement with the inclusion of EEP in the simulations. Northern near‐hemispheric decreases of column NO2 of ≈ 35% observed by SAGE II between early 1985 and 1987 are well simulated with the inclusion of EEP. Comparisons of several simulations with one another and with SAGE II NO2 data and Solar Backscattered Ultraviolet (SBUV) (V6) O3 data suggest that SOLACE represents a solar‐ terrestrial coupling mechanism which, for solar cycle 21, is as important to stratospheric O3 as solar UV flux variations.